[CF-Devel] Weather level 5 (Re: Weather needs smoothing)

[crossfire-devel at archives.real-time.com]

As the person who wrote the weather..  just a few comments..

On 30-Jul-2004 Todd Mitchell wrote:
>
     
      Level 5 weather is not just weather but erosion/climate as well I think - it
     
     >
     
      is
     
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      a lot to process on the maps beacuse it would change ground arches such as
     
     >
     
      swamp to desert as well as do 'weather'.  There are still a few places
     
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      (mostly
     
     >
     
      cities) where there are no elevation of the landscape as well which may or
     
     >
     
      may
     
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      not be a problem for the code.  In the least it will result in very active
     
     >
     
      weather as it will be a big hole in the elevation map.
     
     
Level 4 and 5 never fully worked.  There were too many elevation holes on the
maps, and I never got the feathering routines worked out.  It's insanely
difficult to essentially backport a weather system into a game that was never
designed for multiple-layered tiles.  You end up with all kinds of artifacts
because of the 3-layer limit, and therefore I had to do alot of silly hacking
to make it work better.

As for the rain blobs.. I didn't draw them..  not my fault. :)

>
     
       Weather is still
     
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      somewhat experimental (and anything above level 3 I had problems with in the
     
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      past) I believe so there could be leaks or whatnot as well I suppose.  There
     
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      may be problems with the feathering code as well but I would have to check
     
     >
     
      the
     
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      archives to remember that.
     
     
Basically.. level 3 worked decently last time I tried, which was quite awhile
ago.. so other changes may have broken it over time.  Level 4 and 5 never
really got off the ground, and really just shouldn't be used.  They are
essentially unfinished.

As for the complaints regarding the layout of the equator, it is fairly easy to
move the equator.  You should be able to simply move it to a map edge without
much work.  The equator was originally designed for a much larger bigworld map,
but Mark scaled the bigworld down after I had allready tuned the equasions..
and I never got around to re-fiddling them.

There are probably some misconceptions about the gulfstream, and the other
aspects.  The code is relatively simple.. it simply has two truly random
factors, and then everything else is derrived.

You start with a random pressure.  Pressure affects windspeed.  Windspeed
affects effecitve temperature (windchill) and basically moves humidity around
from the shores.  However, just pressure alone does not properly move humidity
enough from the coasts, therefore the gulfstream was added to push humidity
inland.  Temperature is based on distance from equator, season, and time of
day. Without the gulf stream, the map stagnates and the entire world becomes a
desert bordered by swampland.

Once you have temperature, windspeed, pressure and humidity, you simply combine
those four numbers on a basic chart, to determine the weather.  High temp, low
pressure, high humidity, high wind == hurricane.

I don't think getting level 5 working will ever really be possible.  It
basically means you have to toss out the entire map, and randomly generate one.
People weren't thrilled with the idea, and in order to make it really work, I
think you will have to change a number of basics in the game.  In addition,
elevation was trashed on most of the maps..   You can make it grow trees..
thats pretty easy.. but by letting it do that, that means whole forests are
going to change position.  This will screw up the placement of map entrances. 
I think to make level 5 work, you need to make a commitment to a fully
dynamically generated bigworld, and I think most people do not want that. 

---
Tim Rightnour <
     
     root at garbled.net
     
     >
NetBSD: Free multi-architecture OS 
     
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